JP2010-138796A discloses an abnormality diagnosing apparatus for diagnosing presence of abnormality of two intake air temperature sensors provided in an upstream intake air passage and a downstream intake air passage of a turbocharger, respectively, in an internal combustion engine with turbocharger.
In this abnormality diagnosing apparatus, in order to ensure diagnosis accuracy of abnormality diagnosis, the abnormality diagnosis of the intake air temperature sensor is conducted in a state in which a supercharging pressure is less than a predetermined pressure is kept for a predetermined period of time and a detected value of the downstream intake air temperature sensor is made stable alter lowering of a downstream intake air temperature is finished.